<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <style>
        *{
            margin: 0 ;
            padding: 0;
        }
        .box{
            width: 100%;
            display: flex;
            flex-wrap: wrap;
            /*align-items: center; 纵轴*/
            /*justify-content: center;   横轴*/

        }
        .box div{
            width: 30%;
            height: 100px;
            border: 1px solid black;

        }

    </style>
    <title></title>
</head>
<body>
<div class="pageindex">
   <div class="box">
       <div></div>
       <div></div>
       <div></div>
       <div></div>
       <div></div>
       <div></div>
       <div></div>
   </div>
</div>
</body>
</html>